Fear is a factor in there as well. Fear of being found out in their ignorance of how to do something or to understand the easiest of instruction and inquiries.

I'm not in Bangkok, but where ever you are in the sticks for sure your perfect Thai will not get you anywhere until they deem you not a threat to their cosy insular little world.

For sure my Thai ain't good enough to understand everything by a long way, but I would not want to listen to the banal conversations of most village folk.

Why,what, where,who, when and how questions are best left as reciprocal.